We plan to continue to study a series of strains of Dictyostelium discideum which carry mutations in stk A which we have isolated. Mutations at this locus on linkage group II result in aberrations in cell proportioning such that all the cells differentiate into stalk cells while spores are not made. We want to define the stage at which they diverge from the wild type biochemical pattern by 2-D gel analysis of late proteins. We will focus on the spore coat proteins. We are screening for mutant strains which are defective in the heat shock response so as to define the physiological roles of the heat shock proteins. Mutations will be mapped and revertants selected. We will characterize the mutant and wild-type proteins.